PIV Study Of Flow Structure In A Stirred Tank

Mixing process is important unit operation in chemical engineering andmetallurgical industry, and mixing equipments are widely used in chemicalengineering, food industry, petrochemical projects, biotechnology andpharmaceutical engineering and other fields to strengthen the single ormultiphase fluid in dispersion, mixing and reaction. As the various purposes ofmixing and the complexity of mixing reactions, there are still manyquestions in the current mixing technology. In order to control the mixing andreactions effectively, it is necessary to understand and predict flow stirred tankstructure.Particle Image Velocimetry (PIV) is used to study the flow field in stirredtank with Rushton turbine and full baffles. Particle images are captured at sixdifferent blade positions under the condition of Reynolds number being6.2×10~4, the mean and the phase-averaged velocity fields are obtained, and theturbulent kinetic energy distribution profiles are also presented. The resultsshowed that radial jet flow of Rushton turbine along the radial direction istilted to the top. Closing to the impeller tip, the radial velocity is higher thanother parts. Away from the blade tip, radial velocity is getting smaller and smaller. Nearing the impeller the turbulent kinetic energy is growing first ,thendescending.The influence of impeller diameter is also studies in the thesis. Theimpeller diameter has no influence on velocity and turbulent kinetic energy ofimpeller stream, but affects on the input power, shear velocity, pumpingcapabilities and the radial jet angle.